You start trying to figure out how or why a person is doing what they're doing, as if there's an explanation for it within the context of them being really wrong.
You try to "understand" what is wrong with them. You try to put the pieces together and make sense of why this person is "obviously being ego".
We can get really adamant about this, trying to explain, justify, rationalize.
What we're trying to do is to maintain a consistent sense of what is true. We see something and we believe it's the truth but something about it doesn't add-up and we don't know why. Something doesn't fit. But we don't know that its our own projection that is mistaken, we just think the other person doesn't fit into the truth. They must be wrong because they aren't doing what your truth is saying they should be doing.
The thing is, they might not be fitting in with what you think the truth should be, because your idea of what the truth should be is mistaken. Maybe they are in fact being aligned with the truth, and you are not, and because you're not, you cannot recognize that they are.
So we find other people to be wrong when they are not wrong, because we are wrong. And we only see people as wrong because we're trying to make the truth be something it isn't. We're not seeing straight. We're misinterpreting reality. We're misinterpreting God.
It can be convincing, but we have to realize at some point, maybe this... which seems to be totally true, is not actually the whole truth. Maybe what I think is real and true is actually false, and I'm not seeing correctly. I need correction. Holy Spirit help!